Plastic woven bags
are made of polypropylene (PP) as the main raw material through extrusion, wire drawing, weaving, and bag making. PP is a semi-transparent and semi-crystalline thermoplastic with high strength, good insulation, low water absorption, high heat setting temperature, low density and high crystallinity. It is the main material for making woven bags. Modified fillers usually include glass fibers, mineral fillers, thermoplastic rubber, etc. Plastic woven bags
are widely used. At present, plastic woven bags are mainly used for agricultural products packaging, cement bags packaging, food packaging, geotechnical engineering, tourism transportation, flood materials and so on. There are three main types of woven bags: plastic woven bags (non-laminated woven bags), composite plastic woven bags and various woven fabrics. Production process of plastic woven bags: woven fabrics become woven bags by printing, cutting and sewing. Depending on the equipment used, it can be cut before printing or printed before cutting. Automatic cutting and sewing can continuously complete the process of printing, cutting, sewing. It can also be made into valve pockets, bottom bags, etc. For plain cloth, it can be sewed and bonded to make bags.
Production process of composite plastic woven bags
: woven fabrics, coated with compound materials and paper or film, are compounded or coated. The obtained barrel cloth or sheet cloth can be cut, printed, sewed and made into ordinary sewing bottom bags. It can also be punched, folded, cut, printed and sewed into cement bags. The obtained sheet cloth can be sewed, bonded, printed, cut, pasted and made into paste bottom bags. It can also be welded, rolled and made into tarpaulins and geotextiles. Flat fabrics can be coated or uncoated to produce tarpaulins, geotextiles and other cylindrical fabrics can also be coated or uncoated to produce tarpaulins or geotextiles, etc.
The technical indexes of flat wire production are mainly divided into four categories.
(1) Physical and chemical modification index. There is mainly blending modification, blending ratio, functional additives addition ratio and waste recycled material blending ratio.
(2) Physical property rheological index. There is drafting ratio, blowing ratio, drafting ratio and retraction ratio.
(3) Mechanical performance indicators. The main factors are breaking force, relative breaking force, breaking elongation, linear velocity and linear density deviation.
(4) Tolerance dimension index. There is mainly flat wire thickness, flat wire width and so on.
The polyethylene material in the inner liner bag process is heated by the extruder and melted and plasticized to stabilize the extrusion. It is extruded into a cylindrical film through the die and inflated by compressed air to form a tube bubble. It is cooled and finalized by cooling air ring and pulled into herringbone splint to fold. It passes through traction roll, transmission roll to winding roll. Then the production of inner liner bags is completed by cutting and thermo-closing processes. Finally, bagging of pure polypropylene for filament drawing can not meet the requirements, and a certain proportion of high-pressure polyethylene, calcium carbonate and color masterbatch must be added. Adding a small amount of high-pressure polyethylene can reduce the viscosity and melting speed of material flow during extrusion, increase the fluidity, improve the toughness and softness of flat yarn and woven bags, maintain a certain elongation at break, and improve the low-temperature impact of polypropylene.
The addition of grafted polypropylene can reduce the processing temperature and pressure. Increasing the flow and adhesion of materials can also improve the tensile strength. The addition of calcium carbonate can change the transparent and opaque defects, reduce the harmful static electricity caused by friction in the process of drawing and weaving, increase the ink adhesion of printed trademark patterns, and reduce the natural shrinkage and cost of finished products during storage.